QUANZHOU WOUXUN ELECTRONICS CO., LTD Model: KG-689
Version: KG-689-0801-V1 Page 8 of 35
BATT
P-TX
T171
T181
5T
T181
T181
T181
RX
ANT
TXin
APC
D146
D215
D216
Chart 5
Circuit Description
4. Select transmit and receive circuit
As shown in Chart 5. Output transmit signal will pass transmit and/or receive switch circuit and low-pass,
then send to antenna. Transmit and/or receive circuit has made up of D146 D145 D216. Start during
transmitting and stop during receiving, switch transmitting system and receiving system.
Auto power control circuit APC, use for get a reliable transmit power and transmit control output. This circuit
check out power discreteness end terminal current exhaust and control transmit output. Two reference
voltage from U170, one is give birth to the voltage which use for adjust the power output(AD1 give birth to ),
the other one is get the R171-R173 two terminal and end terminal exhaust current be direct ratio check out
voltage. On the output terminal of U181 can get a reference voltage and check out voltage dispersion be
direct ratio voltage signal. This signal by reverse then as APC voltage. This voltage be use control power
discreteness’ power control feet and make transmit output level off.
As show in Chart 5
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